Manufacture of long haul waveguide



Aug. 11, 1964 A. E. KARBOWIAK MANUFACTURE OF LONG HAUL WAVEGUIDE 5 Sheets-Sheet 1 Filed June 24, 1959 g- 11, 1964 A. E. KARowlAK 3,144,072

MANUFACTURE OF LONG HAUL WAVEGUIDE Filed June 24, 1959 3 Sheets-Sheet 2 2 FIG. 2 ls%\ 2 ///////////////$1N QQEQUCDQ @QQQQ 1954 A. E. KARBOWIAK 3,144,072

MANUFACTURE OF LONG HAUL WAVEGUIDE Filed June 24, 1959 3 Sheets-Sheet 3 By W MQ Attorney United States Patent 3,144,072 MANUFACTURE OF LONG HAUL WAVEGUIDE Antoni Emil Karbowiak, London, England, assignor to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed June 24, 1959, Ser. No. 822,564 Claims priority, application Great Britain July 15, 1958 4 Claims. (Cl. 15367) This invention relates to a process and apparatus for continuous manufacture of circular waveguides intended for the propagation of energy in the circular H mode.

In British Patent No. 780,503 issued Nov. 27, 1957, to L. Lewin et al. there is described a construction in which a waveguide is formed as a helix of fine wire wound with the successive turns in peripheral contact, the axis of the helix being the longitudinal axis of the guide. It is to be understood that the primary purpose of the waveguides under consideration is to provide intercity communication circuits and that the diameter of the waveguides must be considerable as for example, of the order of three inches or 7.5 cm. The distances between the termini of the guides also may be considerable and are measured in miles or kilometres.

It is well known that a circular guide carrying the H mode has the advantage that the attenuation is extremely low but it is also well known that even slight bends in the guide lead to loss of power as the H mode is degenerate with the E mode. As is fully explained in the above mentioned British Patent 780,503, this loss of power can be reduced by a construction in which the surface impedance at the interface between the conducting wall of the guide and the wave transmission medium (in practice the air or gas within the guide) is anisotropic in such a way that the propagation of the H wave is facilitated while that of other modes is inhibited.

The particular form of cylindrical guide described in that specification, in the form of a helix of fine wire with the adjacent turns in peripheral contact is very practical and is the preferred embodiment of the construction.

British patent application No. 7745/57 filed Mar. 8, 1957, in the name of A. W. Gent et al. describes and claims a process for the manufacture of a circular waveguide comprising the steps of winding a metal wire on a cylindrical mandrel to form a helix with the successive turns in peripheral contact, holding the successive turns of the helix together whilst still on the mandrel by means including the application of an adhesive and the subsequent setting thereof, and pressing the helix gradually along the mandrel and off the end thereof.

The above mentioned patent application also describes and claims a process for the manufacture of a circular waveguide comprising the steps of winding a metal wire on a cylindrical mandrel to form a first helix with its successive turns in peripheral contact, applying a further winding around said first helix to form a second helix with its successive turns laid in the grooves between the successive windings of the said first helix, holding together successive turns of the helices whilst still on the mandrel by mean including the application of an adhesive material and the subsequent setting thereof, pressing the double helix so formed gradually along the cylindrical mandrel and off the end thereof.

The process and apparatus described in the above mentioned specification is however suitable only for making a succession of relatively short finite lengths which will later be joined together to form a continuous length of waveguide.

It is the object of the present invention to provide a process and apparatus for producing a helically wound wave guide in comparatively long lengths.

3,144,072 Patented Aug. 11, 1964 The process and apparatus described hereinafter are adaptable to the production of a wave guide in a continuous length on the route in which the wave guide is to be installed in such manner that the guide may be manufactured as it is being installed.

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 shows schematically apparatus for carrying out the invention,

FIG. 2 shows a longitudinal cross-section of part of a segmented mandrel supported on ball races,

FIG. 3 shows in vertical cross-section the segmented mandrel supported on its ball races,

FIG. 4 shows the inter-engaging segments of which the mandrel is built up,

FIGS. 5 and 6 show part of an inter-engaging segment in detail,

FIG. 7 represents a simple form of segment extractor,

REG. 8 represents diagrammatically the elevation of apparatus for the continuous manufacture and installing of a wave guide, and

FIG. 9 shows a plan of the apparatus of FIG. 8.

In FIG. 1 the machine is shown schematically in operation. A hollow cylindrical steel core 1 is fixed to a support 10 and is of any convenient length say 3 to 6 feet and carries a large number of ball-races 12 (or some other suitable elements) disposed uniformly in the surface of the core, as shown in greater detail in FIGS. 2 and 3.

The core 1 serves as a carrier for a segmented mandrel 2. This mandrel is in essence a precision ground steel tube made up of identical interlocking segments 13. Each of these segments is part of a helix and, as shown in FIGS. 4, 5 and 6, the whole assembly of segments constitutes a cylindrical mandrel held together by the tongue and groove construction of the segments. The segmented mandrel fits over the core 1 with a very small clearance and can slide with ease along the core on the said ball-races.

The winding head 4 revolves coaxially around the mandrel and is supported by the member 5.. The winding head carries a set of ball-races 6 (or other suitableelements) set in such a manner that a surface tangent thereto has a lay angle equal to the lay of the helical wave guide to be produced. The winding head is equipped with radial arms 3 which carry the reels of wire used in the formation of an inner helix 7 and an outer helix 8 with its successive turns laid in the grooves between the windings of the inner helix 7.

While the drawings illustrate a double helix of fine wires bound together with a suitable adhesive it has been found that a satisfactory guide can be formed as a single helix with the successive turns held together by the adhesive. The same adhesive is used to hold the protective coatings 9 referred to below around the guide.

A tool 17 shown in simple form in FIG. 7 which will be referred to as a segment extractor may take many possible shapes and forms, but essentially it is needed, as described below, for extracting the last mandrel segment.

The operation of the machine is as follows: When in use the winding head 4 and with it the radial arms carrying the reels of wire are made to revolve on the supporting member 5. In this way the wire is fed under rollers 6 and, since the winding head is prevented from moving axially relative to the core 1 by the member 5, the segmented mandrel assembly together with the already manufactured length of waveguide is constrained to slide to the right in FIG. 1, while supported by the plurality of ballraces 12 carried by the core. To assist in this process and to avoid excessive forces on the winding head the payout roller 11 is frictionally power-driven.

During this process additional winding heads (not showh) are made to feed cotton tapes, steel armouring V. 3 tapes, shown at 9 in FIG. 1 etc., onto the waveguide. An adhesive, as described in British application No. 7745/57 above referred to is applied to the two helices 7 and 8 if a double helix is used and a suitable binding agent or adhesive is fed continuously between the layers being applied, outside the double helix, so that after this binding agent is set a self-supporting structure is formed. While the waveguide winding is proceeding, at suitable intervals of time, a segment extractor 17 is passed down the centre of the hollow core from the left in FIG. 1 to reach the last segment 16 of the mandrel, and made to engage in the locking aperture 14, FIG. 5. With a slight forward movement the last segment is disengaged, without disturbance'of the thus-far formed helix and brought back along the hollow core, to be subsequently placed at the beginning of the mandrel where it is again locked in position to be used again and so on. In FIG. 7 there is shown a simple form of segment extractor 17 having a turned up end 18 which can engage with the aperture 14 indicated in the last segment shown in FIG. 5. The extractor tool can be manipulated to disengage the last segment from the end of the segmented mandrel.

While the said last segment is in process of being removed from the inside of the waveguide another similar segment extractor is made to hold the second-to-last segment to prevent it from being dislodged. In a subsequent movement this segment extractor will be used for extracting that segment. a

This process is repeated indefinitely and the waveguide can be paid out directly into a prepared trench, if the machine is mounted on a suitable truck.

When the formed waveguide has left the mandrel it is supported on suitable pay out rollers of which the first one is indicated in FIG. 1 by the reference numeral 11.

The binding agent mentioned above can belong to one of the two classes (i) a liquid that sets hard because the solvent is allowed to evaporate. (ii) a liquid that changes into a solid because of chemical reactions taking place between the components of the liquid or because of chemical reaction between the liquid and the outside atmosphere. For example, various cellulose solutions belong to the first class while epoxy resins are representative of the second class.

From the point of view of waveguide manufacture,

however, the choice of a particular kind of binding agent is only a matter of convenience, but what is important is the setting time of the binding agent, which is its chief characteristic and which fixes an upper limit to the rate of waveguide production. As long as the binding agent remains soft the waveguide must be supported on the rigid mandrel and it is only when the binding agent becomes hard that the mandrel may be removed, if a waveguide free from distortion is to be produced. If 1 is the mandrel length in feet and t the setting time of the binding agent in minutes then evidently the maximum rate of waveguide production on a solid mandrel will be 1/ t feet per minute as after the binding agent had set it would no longer be possible to slide the formed waveguide off the end of the mandrel.

Some binding agents can be made to set in ten minutes.

The maximum length which could be made on a solid nonrotating mandrel would be about one inch owing to the excessive friction opposing any attempt to slide the completed guide along the mandrel and therefore the maximum production rate would be limited to one inch in each time interval 2 and if this time is 10 minutes the speed of production would be limited to 6 inches per hour which is an impracticably small figure. In the present design, however, the mandrel is made to roll along the ball-races mounted on the core and consequently the mandrel may be of considerable length. Thus with a mandrel feet long the rate of production is as high as 30 feet/hour which is a very acceptable figure.

It will be appreciated that the mandrel is itself continuously replaced by the removal of segments from its distant end and their replacement at the near end and accordingly the invention provides a practical process of manufacturing waveguide on site of any desired length.

In FIGS. 8 and 9 there is illustrated a machine suitable for laying wave guide straight into a prepared trench from a truck mou nted on rails and straddling the track. It must be noted that waveguide manufactured according to the invention has a small but limited degree of flexibility owing to the elasticity of the conductive material and of the adhesive.

FIG. 8 is an elevation view of the machine while FIG. 9 is a plan view corresponding to FIG. 8.

As will be understood a long haul waveguide has'to be laid along a fairly straight track as even minor deviations result in deterioration of the transmission. Therefore the waveguide making machine, which is not of great size, is mounted on a mobile platform which is caused to travel along the prepared route paying out the waveguide into the prepared trench.

In FIG. 8 there is shown a mobile platform 19 mounted on two bogies 20 each carried on four wheels 21. These wheels 21 run along a temporary railway track 22 which has been laid straddling the route of the waveguide. The platform 19 is therefore able to run along the rail track 22. This track 22 has been constructed so that one rail lies on each side of the prepared bed for the wave-guide which is in a trench 23. As shown in FIGS; 8 and 9 there are rollers 24 straddling the trench 23 on which the waveguide 25 is laid as the manufacture proceeds. This provides'for convenient inspection and the guide can then be lowered into the trench 23 when the rollers 24 are removed.

On the mobile platform 19 there are mounted, in the embodiment shown, a pair of short rails 26 (see FIG. 9) and on these there is mounted a subsidiarycarriage 27 also on wheels 28 running on the rails 26. On this carriage 27 there is mounted the waveguide forming unit 29 which'comprises the apparatus shown in FIG. 1 of the accompanying drawings.

- The waveguide 30 as it is formed passes first onto rollers 31 on the subsidiary platform 27 and then onto rollers 32, mounted on raised supports where necessary, carried on the main mobile platform 19.

The complete machine is operated as follows: The subsidiary carriage 27 is brought as far to the right (in FIG. 8) as practicable and the waveguide-forming unit 29 is put into operation. It will be remembered that the production rate is about 30 feet per hour. As the waveguide is formed it is paid out onto rollers 31 on the subsidiary carriage and then onto the rollers 32 on the main carriage As the waveguide is being formed the subsidiary carriage 27 is slowly moved along the rails 26 towards the left in FIG; 8. At suitable intervals the main platform 19 can be moved to the left and the subsidiary platform 27 brought back to'its initial position. It must be appreciated that the previously formed length of waveguide may be lying on the rollers 24 or may have been lowered into the trench 23 so that any fresh guide produced can only be taken up by movement of the platforms 19 and 27.

In practiceit is possible to drive the platform 19 to the left at precisely the speed of production of the guide so that platform 27. is not absolutely essential but it is preferably provided for convenience and to allow for very fine adjustment of the speed of travel. I

In order to allow of fully automatic production it is preferred to drive platform 27 in synchronism with the production of waveguide. 1 When platform 27 approaches the leftmost extremity of its travel it trips switches which cause platform 19 to be driven to the left at a somewhat higher speed than the progress of platform 27 until it tripsswitches and stops. This point of stopping is selected so that platform 27 is now in its initial position with respect to platform 19.

This sequence of operations can be repeated indefinitely so as to provide continuous production of Waveguide along the selected route which renders waveguide jointing unnecessary, and thus avoids a diflicult and troublesome operation.

While the principles of the invention have been described above in connection with specific embodiments, and particular modifications thereof, it is to be clearly understood that this description is made only by Way of example and not as a limitation on the scope of the invention.

What I claim is:

1. Apparatus for use in the continuous manufacture in situ, of a circular waveguide formed of a wire helix comprising a cylindrical core, a plurality of ball-races mounted in the wall of said core so that they project slightly from the outer surface of said core, winding means mounted in a fixed axial relation to said core and a collapsible mandrel adapted to be carried on said ball-races, said ball-races and said mandrel movable axially with respect to one another proportionately to the formation of said waveguide without disturbance of the thus-far formed waveguide by virtue of the collapse of said segments of said mandrel at the forward end thereof, and the extraction of said collapsed segments.

2. Apparatus according to claim 1 wherein said mandrel includes a plurality of interlocking segments each adapted to be unlocked from within by an extractor tool which is capable of being passed down the hollow center of said cylindrical core and which is capable of detaching the segment at the forward end of said mandrel and of extracting said forward segment back through said hollow center.

3. Apparatus according to claim 1 further comprising a vehicle having supporting means for supporting said cylindrical core, guiding means for controlling the path of said vehicle, and means supported on said vehicle and along the path of said vehicle for guiding the formed waveguide in a desired manner away from said collapsible mandrel to a position along said path.

4. Apparatus for producing a continuous long circular waveguide from a supply of fine wire comprising a stationary hollow cylindrical core having a length which is small in relation to the total desired length of waveguide, a plurality of ball-races mounted on said core and extending from the outer surface of said core, a mandrel slidably mounted over said core on the said ball-races and extending axially beyond said core so as to extend the effective supporting length of said core, said mandrel comprising a plurality of interlocked segments each capable of passing through the interior of said core and each having an associated surface characteristic which permits detachment thereof from within said core, wire winding means mounted for rotation about said core in fixed axial relation thereto, and means attached to said winding means for guiding wire in helical turns onto said mandrel.

References Cited in the file of this patent UNITED STATES PATENTS 2,605,202 Reynolds July 29, 1952 2,657,364 Carr Oct. 27, 1953 2,714,414 DeGanahl et al Aug. 2, 1955 2,731,067 Miller Ian. 17, 1956 2,751,318 Speekman June 19, 1956 2,771,386 Merz et a1. Nov. 20, 1956 2,828,239 Fischer Mar. 25, 1958 2,836,370 Drees et al May 27, 1958 2,959,367 Kuba et al. Nov. 8, 1960 FOREIGN PATENTS 179,386 Great Britain May 11, 1922 

1. APPARATUS FOR USE IN THE CONTINUOUS MANUFACTURE IN SITU, OF A CIRCULAR WAVEGUIDE FORMED OF A WIRE HELIX COMPRISING A CYLINDRICAL CORE, A PLURALITY OF BALL-RACES MOUNTED IN THE WALL OF SAID CORE SO THAT THEY PROJECT SLIGHTLY FROM THE OUTER SURFACE OF SAID CORE, WINDING MEANS MOUNTED IN A FIXED AXIAL RELATION TO SAID CORE AND A COLLAPSIBLE MANDREL ADAPTED TO BE CARRIED ON SAID BALL-RACES, SAID BALL-RACES AND SAID MANDREL MOVABLE AXIALLY WITH RESPECT TO ONE ANOTHER PROPORTIONATELY TO THE FORMATION OF SAID WAVEGUIDE WITHOUT DISTURBANCE OF THE THUS-FAR FORMED WAVEGUIDE BY VIRTUE OF THE COLLAPSE OF SAID SEGMENTS OF SAID MANDREL AT THE FORWARD END THEREOF, AND THE EXTRACTION OF SAID COLLAPSED SEGMENTS. 